Posts Tagged ‘20:22’

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu

Downy mildew on pumpkin and butternut squash is now present in many fields in Maryland and Delaware. Growers should scout their fields carefully. Preventative sprays are more effective than fungicides applied after the disease is established. On the lower surface the lesions are brown and angular. If viewed through a good hand lens, black flecks, which are the sporangia, may be visible. On the upper surface of the leaves the symptoms are more general and mimic many other diseases. Lesions on the upper surface appear as yellow angular spots that eventually turn brown and necrotic. Also, be aware that powdery mildew is also abundant in fields. Powdery mildew will appear as white granular spots, and is also prevalent on the leaves pictured below.

Downy mildew lesions lower surface

Downy mildew lesions upper surface

There are several fungicides registered for managing downy mildew. The “targeted” products below should all be used in a tank mix with protectant product such as chlorothalonil or mancozeb. (These products are not effective on powdery mildew, so remember to include a product to control powdery mildew, also.)

The potential for significant populations of corn earworm, beet armyworm and in some cases soybean loopers remains high in fall vegetable crops statewide. Moths can be found laying eggs in fields so you may need to scout fields at least twice a week as well as check local trap catches on our website for corn earworm and corn borer (http://ag.udel.edu/extension/IPM/traps/latestblt.html) or call the Crop Pest Hotline in state: (800) 345-7544; out of state: (302) 831-8851.

Cole Crops
Continue to sample for cabbage looper, diamondback larvae, beet armyworm, fall armyworm and Harlequin bug. Although the pyrethroids will provide control of Harlequin bugs they are not effective on beet armyworm or diamondback. Be sure to scout and select controls options based on the complex of insects present in the field.

Lima Beans
Continue to scout for stink bugs, lygus bugs and corn earworm. A treatment will be needed if you find one corn earworm larvae per 6 ft-of-row. With the increase in local corn earworm catches we are starting to see a significant increase in larval populations. We have also found soybean loopers in lima bean fields. Remember that they are a migratory pest, difficult to control and pyrethroid resistance has been documented in states to our south. The Belt SC, Besiege and Lannate labels list soybean looper or looper species control on the label. Be sure to check the label for rates, restrictions (including plant back/rotational crop restrictions) and days from last application to harvest.

Melons
Continue to scout all melons for aphids, cucumber beetles, and spider mites. We continue to see a significant increase in aphid populations. Treatments should be applied before populations explode and leaf curling occurs.

Peppers
At this time of year, corn borer, corn earworm, beet armyworm and fall armyworm are all potential problems in peppers. So be sure to select the material that will control the complex of insects present in the field. Be sure to check local moth catches in your area by calling the Crop Pest Hotline (in state: 800-345-7544; out of state: 302-831-8851) or our webpage at http://ag.udel.edu/extension/IPM/traps/latestblt.html. We continue to see aphid populations increasing, especially in fields where pyrethroids have been used on a weekly basis. Labeled materials are only effective if applied before populations explode.

Snap Beans
With the high trap catches, you will need to consider a treatment for both corn borer and corn earworm. You should also watch for beet armyworms and soybean loopers. Sprays are needed at the bud and pin stages on processing beans for worm control. With the diversity of worm pest that may be present in fields, be sure to scout fields and select materials that will control the complex of insects present. You will need to check our website for the most recent trap catches to help decide on the spray interval between the pin stage and harvest for processing snap beans (http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/snapbeanecbthresh.html).

Spinach
As the earliest planted spinach emerges from the ground, be sure to watch for webworms and beet armyworms. Both moths are active at this time and controls need to be applied when worms are small and before they have moved deep into the hearts of the plants. We are starting to see an increase in beet armyworm populations being found in all vegetable crops – so it will also be important to select a material that will provide beet armyworm control. As a reminder, the pyrethroids have not provided effective beet armyworm control in past years. Since webworm populations are generally heavier during hot, dry seasons, it is important to apply controls before any webbing occurs. Remember that both insects can produce webbing on the plants. Generally, at least 2 applications are needed to achieve control of webworms and beet armyworm.

Sweet Corn
With the continued high corn earworm trap catches, be sure that a spray is applied as soon as ear shanks are visible on plants. If fall armyworms are present in the whorl, you will need multiple whorl sprays for this insect before the ear shank spray to achieve effective control and to prevent larvae from dropping into the ear zone. Once fields are silking, you will need to check both blacklight and pheromone trap catches for silk spray schedules since the spray schedules can quickly change. Trap catches are generally updated on Tuesday and Friday mornings (http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/silkspraythresh.html). You can also call the Crop Pest Hotline (in state: 800-345-7544; out of state: 302-831-8851). Be sure to check all labels for days to harvest and maximum amount allowed per acre.

Nearly 50% of the nation’s farmers’ crops have suffered losses from extremely dry conditions during the current growing season. Sharply rising prices and crop devastation will affect not just producers themselves, but all channels of the U.S. and global economies. Therefore, it is important Delaware farmers stay informed about risk management and farm safety-net options available to them, in order to keep funds available and cash flow steady.

Two workshops are to be held on September 17, 2012 featuring discussion and instruction on crop insurance, grain marketing, pending ag legislation, and general risk management.Admission is free and each meeting includes complementary risk management related materials and refreshments.

To register for either event please call 302-424-8340 or 877-673-2767 (registration is not required, but ensures availability of materials for all attendants). Setting aside the time to attend may save you time and money in the future.

6 p.m.: Social & Fundraiser including a silent auction for “Save Farm Families” coordinated by the Mid-Atlantic Soybean Association. Join us for specials on food and beverages at The Brick Hotel, 18 The Circle, Georgetown, Del.

This event is FREE, but please register by August 15 to help us prepare for meals.

To register contact Karen Adams at (302) 856-2585 ext. 540 or by email at adams@udel.edu. You can also register by eFax at (302) 264-8638 or online at: www.desoybeans.org.

Cooperative Extension programs and employment are available to all without discrimination. Evidence of noncompliance may be reported through your local Cooperative Extension Office. If you have special needs that need to be accommodated, please contact the office two weeks prior to the event.